Dreading traffic jams this holiday season? There are apps for that. The advent of GPS-enabled cellphones has generated a wave of applications, many of them free, that turn drivers into veritable traffic reporters.

Here’s how they work: Your GPS-enabled phone automatically transmits bits of data to Waze, Inrix, Google and other traffic app makers that show where you are and how fast you’re moving. Some apps also allow users to report accidents, closed roads or construction (when parked or in standstill traffic, of course). Each company then combines the information to get an idea of traffic conditions and distributes that across its network. Call it crowd-sourcing from your car. While you are fuming in traffic on I-95, other drivers can benefit from that information and avoid getting stuck themselves. In turn, you get free traffic reports from other users. “It’s real-time traffic, not just where there are road sensors but anywhere anyone is driving,” said Di-Ann Eisnor, a vice president at Waze, a start-up based in Raanana, Israel. Waze has been adopted by about 550,000 users since it became available in the United States last summer. Before GPS-enabled cellphones, traffic reporting companies like Inrix relied on data from road sensors, police scanners, commercial truck fleets outfitted with GPS tracking devices, and other sources. But even with such a wide range of information there were gaps in traffic coverage. Road sensors are found only along sections of major highways, for example, not along back routes that get tied up during apple-picking season. That’s where crowd sourcing comes in. “No matter where those consumers go, it allows us to get speed data for all the roads they travel,” said Jim Bak, a spokesman for Inrix, a traffic services company based in Kirkland, Wash. That data includes “backroads and arterial city streets,” he added. Worried your speed might get back to the authorities? Each company emphasizes that your identity isn’t compromised. “All we’re getting back is: 50 cars passed through a stretch of road all going this speed,” Mr. Bak said. “I don’t know whose phone or I.P. address or user it is.” With the Thanksgiving holiday season coming up, I wanted to see how well these apps worked on a route I knew well. So I downloaded three free apps — Waze, Google Maps and Inrix Traffic — to my Android phone and, with my husband at the wheel, took them for a test drive to Grandma’s house in upstate New York on a Friday night in late October — at the height of rush hour. Each app, which is also available on the iPhone, offered a decent overview of road conditions for major routes and, perhaps more notably, immediate gratification: Instead of waiting for the radio traffic report, I powered up an app to get an instant idea of traffic conditions. None offered Riverside Drive as a way to get around traffic on the West Side Highway — which is what any New Yorker with a car would have recommended during rush-hour traffic. Asking Google Google Maps turns your phone into a navigation system with voice-guided driving directions and offered the best at-a-glance display of road conditions. Opening up the maps application in Midtown Manhattan, I got a bird’s-eye view of traffic across much of the city and along bridges and tunnels to New Jersey. Color-coded lines corresponded to the intensity of traffic: green for no traffic jams, yellow for medium congestion, red for heavy congestion, and red and black for stop-and-go traffic. Not surprisingly, at 5 on a Friday evening, the Lincoln Tunnel and West Side Highway were blazing red. To determine which way to go I plugged in my destination and Google Maps spit back a snapshot of a route through the Lincoln Tunnel and Route 23 North in New Jersey. Estimated drive time: 1 hour, 55 minutes. But who wants to sit in traffic in the tunnel? I selected the icon for alternate routes and was offered two options, both of which bumped the drive time up by a few minutes. I chose the one over the George Washington Bridge — if I was going to get stuck in traffic, at least I’d have a view. And the snapshot showed promise. While the West Side Highway was red, the lower level of the bridge was green. At that point, the radio finally looped back to the traffic report, confirming that the West Side Highway was “backed up from the 50’s to the GW.” No matter: we had already decided to take 11th Avenue up to Riverside Drive toward the bridge to speed up the trip. Asking each other Like the Google app, Waze offers voice navigation and traffic conditions. Coverage was lacking on much of my drive, with color-coded arrows indicating speed popping up only occasionally, despite traffic jam alerts from other Wazers (“complete standstill W 49th St.”). And for some reason, the alternate routes function didn’t work for me. Where Waze stood out was the fun factor. Each user starts out as a cartoon “baby wazer” who can “evolve” and gain points by reporting accidents, blocked roads and other traffic issues or by simply driving. Around 125th Street, for example, the app chimed and a message appeared: “You’ve driven 5 miles! Look for a yummy 25 pt. Bonus candy on the map.”

Later, at the ramp to the lower level of the George Washington Bridge, a Waze “road-muncher,” reminiscent of Pac-Man, showed up and started munching the highway, indicating a road that Waze is in the process of mapping out. There was also something therapeutic about blasting alerts to other Wazers while sitting hopelessly in traffic. And it felt good to tell drivers who could be seen sitting in bumper-to-bumper traffic on the West Side Highway of our alternate route on Riverside Drive. Yet you can also see how all these “geo-gaming” elements, as Waze describes them, could cause one of the accidents that showed up on the map. To deter drivers from gaming while driving, Waze said it disables texting while the car is moving. But that can be overridden by selecting O.K. for passenger mode, as I did. Gazing into the future Inrix Traffic was the only app I tried that offered traffic predictions. Selecting “forecast” from the menu allowed me to see what conditions were expected in 15, 30, 45 and 60 minutes, a nifty feature if you’re trying to decide whether to wait for an accident to clear up or forge ahead. For example, the southbound lane of the West Side Highway gradually shifted from red to orange to green over the course of an hour. Unfortunately, we were heading north so that didn’t help us much. Inrix says it offers an upgraded Pro version of its app ($9.99 a year on the iPhone) offering faster, alternate routes for some destinations based on traffic conditions. Unlike Google and Waze, Inrix doesn’t offer a voice navigation feature, but it did take factors into account that could cause traffic like major sporting events. Bottom line Ultimately, none of the apps were as good as I had hoped. Yes, they all offered a decent snapshot of driving conditions with the flick of a finger. But deciphering that snapshot often left me squinting at my phone’s small screen — not something I want to be doing in the driver’s seat. And while I appreciated their immediacy, none of them produced what my husband and I already knew from experience — the quickest way to Grandma’s house.